Manufacture of flexible conduit



Jan. 4, 1938.

G. A. GLEASON MANUFACTURE OF FLEXIBLE CONDUIT Original Filed April 19, 1935 2 Sheets-Sheet 2 Juventa?? @EO/5.15' @LE/@50M @fij/waff,

Patented Jan. 4, l1938 'UNITED STATES PATENT OFFICE 2,104,121 MANUFACTUBE F FLEXIBLE CONDU`IT George A. Gleason, Worcester, Mass., assignor to The American Steel and Wire Company of New Jersey, a corporation of New Jersey Original application April 19, 1935, Serial No. 17,325. Divided and this application February 21, 1936, Serial No. 65,167

a claims (ci. 14o- 11) This invention isa method of making an improved form of flexible conduit of the type frecoil of half-round wire having its normally iiat face inside and upset so that it is appreciablyv` convex, T-wire wound over this coil 'with the stem portion forced inwardly between the convolutions of the half-round wire to an extent sufiicient to at least slightly separate the same but insufficient to become ush with their ,in-

15 side faces and with its head portion extending at least slightly above the outer faces of these convolutions, wires tightly wound with a relatively long-pitched lay over the T-wire so as to contact the latters head portions and continuously force the T-wire to maintain its relationship with the half-round wire and cord-packing which is laid between the 1f-wire and the last mentioned wires so as to iill the interstices between the latter. y The above conduit is illustrated by the accompanying drawings, inwhich:

Figure 1 shows the conduit broken away so as to illustrate its component parts;

Figure 2 shows the specific relationship ofthe parts by means of an enlarged longitudinal section; I

Figure 3 shows a step in themanufacture of the conduit; and

Figures 4 and 5 show a machine suitable forv manufacturing the conduit in plan and elevation,

respectively.

Referring more particularly to these drawings:

- Figures 1 and 2 illustrate a cable I carried by the conduit consisting of the short-pitched heli- Y 40 cal coil of half-round wire 2 having its normally ilat face 2" inside and upset so'that it is appreciably convex. This convexity may be secured during the coiling operation providing the half-round wire 2 is of sumciently large dimensions as compared to the diameter of the helix into which it is formed. The convex faces thus provided are of great advantagein that they materially reducewearA on the cable I r by reducn ing the friction between the parts and by preventing the sharp edges of the -half-round wire from exerting any-,cutting action.

l The T-wire 3 is wound over the coil of halfround wire 2 with its stem portion 3 forced inwardly between the convolutions of the latter to an extent sumcieut to at least slightly separate i the same but insufiicient to itself become flush with their inside faces 2a. This separation of the convolutions provides an internal helical groove for the conduit, which functions as a grease retainervfrom which grease may be distributed to 5 the cable i during the latters reciprocating action. Furthermore,- any flexing of the conduit tends to close this grooveat one point or another whereby any grease in the same is extruded onto the cable. It is also to be noted that the head 1 Y portion 3b of the T-wire 3 extends at least slightly above the outer faces of the convolutions of the half-round wire.

The 'outermost layer of'the conduitY consists 'of the plurality of wires v4 which are tightly 15 wound with a relatively long-pitched lay over 'the T-wire 3 so as to contact the latters head portion 3b and so as to continuously force the T- wire to maintain its relationship with the halfround wire. The cord packing 5 is laid between the T-wre 3 and the wires 4 so as to iill the interstices between the latter. Any tendency of the half-round wire 2 or T-wire 3 to open up due to their short-pitched helical form is prevented -or retarded by these wires 4 due to their rela- 25 tively long pitch. Furthermore, these wires 4 function to greatly increase the tensile strength of the conduit as a whole. They also function to vcontinuously force the T-wire 3 into place so that no openings will occur `when the conduit is ao arced, thisaction being particularly eilective .due to the fact that the head portions 3 ofthe T-wire 3 extend slightly above the outer faces of the convolutions of the half-round wire 2. Since this will in many cases tireiy grease-tight, it. will be possible to entirely -eliminate the cord packing 5 in many instances.

Then too, these wires 4 may be rust-proofed by galvanizing or the like, or they may be made of rust-resisting steel, whereby it will no t be o necessary to paint or otherwise protect the conduit-against rust. Y

All of the wires are preferably made of highcarbon or other-hard steel. This reduces thev wear on the half-roundwireZ and renders the 5 T-wire 3 sufllciently rigid to prevent any shortening of the conduit. The long pitch of the wires 4 effectively dampens the conduit so as to greatly retard any crystallization which might result from vibration. a 50 A new methodj oi" manufacturing is also involved in the making of the conduit which has just been dcri In this method the half-round wire 2 is coiled into a helix in any suitable manner, while the u make the conduit en- '35.

stem portion 3l `and the head portion 3b of the T-wire 3 are originally much thicker than they are when the conduit is complete. In Figure 3 the T-wire is indicated as having such dimensions, this wire being wound over the helix of the half-round wire 2 so that its stem portion 3 extends inwardly between the convolutions oi.' the latter. After this has been done suicient inwardly directed force is applied to the T-wire to cause it to ilow at least slightly, whereby its head portion 3b is thinned, and its stem portion 3* is elongated.

It is to be noted that the" above operation involves an actual working of the T-wire 3, this working tending to take out any recoil. The operation may be accomplished bythe use ofa conventional swaging machine, or by means of pressure rolls of suiiicient strength. It is to be understood that the lnal result is that shown 'by Figure 2.

JAfter the above operation the wires 4 are laid tightly over the T-wire in oppositely pitched relationship. During the laying operation a cohstricting torque is applied to the T'wire and the helix of the half-round wire, the ultimate release of this torque producing a much firmer conduit than Would result if the wires 4 were laid in the usual manner. N

Figures 4 and 5 show a machine which is particularly suited for use in applying the wires l. It is more or less conventional in that it includes a series of spools 6 which are carried by revolubly mounted swivels and provided with suitable parts so as to properly feed the Wires to a stationary die 8. The various revoluble parts are mounted by a hollow shaft 9 through which the assembly consisting of the T- wire and helix of half-round wire-is fed from a spool II). n,

The machine is unconventional in that this spool I0 is carried by a rotary mount II which has no direct connection with the hollow'shai't 9 and which is driven in ajdirection rotatively opposite to the latter. It is by this I and are otherwise arranged' which isA means that the torque is placed on the two inner layers of the conduit during the application of the outer layer, the rotative direction oi the rotary mount I I being in the proper direction to accomplish this result. This mount'may be driven by any suitable means, such as the gearing shown by the drawings and generally indicated by the numeral I2, which interconnects it with the main power shaft I 3 which drives the conventional part of the machine. Preferably, this gearing should include a variable speed drive I2*l whereby varying amounts of torque may be placed upon the conduit structure being fed to the die 8.

I claim:

1. A method of making a flexible conduit,'in ciuding coiling half-round wire into a helix, winding T-wire over said helix so that the stern portions of said T-wire extend inwardly between the convolutions of said half-round wire and applying sumcient inwardly directed forcel to said T`wire to cause it to flow at least slightly, whereby the head portion of said T-wire is thinned and its stem portion is elongated. n

K2. A method of making a flexible conduit, including coiling half-round wire into a helix, winding T-wire over said helix so that the stem portions of said T-wire extend inwardly between the convolutions of saidhalf-round wire and laying wires tightly over said T-wire in oppositely pitched relationship and while applying a constricting torque to said T-wire and said helix.

3. A method of making a exible conduit, including coiling half-round wire into a helix, winding T-wire over said helix so that the stem portions ofsaid T-wirel extend inwardly between the convolutions of said half-round wire, applying sufficient inwardly directed force to said T-wire to cause it to ow at least slightly, whereby the head portion of said T-wire is thinned and its stem portion iselongated, and laying" wires tightly over said T-wire in oppositely pitched relationship and while applying a constricting torque vto said T-wire and said helix.

GEORGE A. GLEASON. 

